(CNN) -- An offshore 6.9 magnitude earthquake and aftershocks shook the coast of Northern California and parts of Oregon on Sunday night, the U.S. Geological Survey said. No major damage or injuries were immediately reported.

The main quake, centered in the Pacific Ocean about 50 miles west of Eureka, California, happened at 10:18 p.m. PT, the USGS said. The depth was about 10 miles.

Mike Meltzer, in Ferndale, just southwest of Eureka, told CNN affiliate KTVU the he felt the quake for about 10 seconds. The only damage that he could see: A bottle fell over.

"I've been through a number of these," Meltzer, a bartender at Ferndale's Hotel Ivanhoe, told KTVU. "It wasn't a jolter; it was a wave."

More than 15 aftershocks were reported in the area within five hours, the strongest of which was a 4.6 magnitude temblor in the ocean, according to the USGS.

The strongest shaking was reported in the Eureka area, with weak motion felt in west-central Oregon and in the San Francisco area, according to the USGS.

There is no tsunami threat, according to the Pacific Tsunami Warning Center.

The shaking drew a number of comments on social media.

"Long rumble, no damage," Twitter user @Amy_Stewart posted. "Forgot to take the cat when we ran outside. Now he knows where he stands."